The invention relates to a method of folding the ends of tubular wrappings.
Conventionally, a wide variety of commodities such as candy, pastilles, cookies, etc. are stacked in units of given number and conveyed into a wrapping machine by which each such stack is enveloped in a sheet of wrapping material; more exactly, the sheet is cut to a length greater than that of the stacked contents and formed into a tubular wrapper around them in such a way as to project beyond the two end surfaces, whereupon the projecting ends are folded in and flattened against these same two surfaces to form the ends of the finished wrapping.
Prior art methods of effecting the end folds in such wrappers consist essentially in rolling the enveloped commodity though a distance equal to the developable length of its transverse surface in such a way as to engage a succession of helically shaped fixed folding elements distributed along the rolling path, by which respective portions of the projecting end of the wrapper are progressively folded against the end of the enveloped commodity, part in direct contact with the end surface of the enveloped commodity, and part overlapping an area of the portion previously folded.
In order to gather the projecting end of a tubular wrapping in such a way that the corresponding end of the package will be both airtight and acceptable in terms of appearance, a significant number of single folds must be made (generally five, in the case of a cylindrical pack); moreover, each of the single folds must be made correctly. Given that, in prior art methods, these folds are effected along a rolling path equal in length to the developable circumference of the wrapping, as mentioned above, it happens that when this developable length is significantly reduced, the number of fixed folders that can be utilized, hence the number of single folds obtainable, must necessarily fall short of the minimum number effectively acceptable.
The result of such a situation is that commodities of relatively limited transverse dimensions tend to produce a package in which the ends of the tubular wrapping appear simply crumpled, and exhibit an irregular, angular profile. The object of the present invention is to overcome the difficulties encountered in gathering the ends of tubular wrappings, as outlined above, through the provision of a method whereby it can be ensured that each of the single folds is correctly made, irrespective of the transverse dimensions of the commodity to be packaged.